PHP - using a recursive function to find the max() of nested arrays

Question

The following code uses a simple strategy for finding the max of the nested array. It uses foreach to find and label the max value, however, if I got an array that was nested t

Answer 1

You can use array_walk_recursive() for it:

function array_max_recursive($arr)
{
    $max = -INF;

    array_walk_recursive($arr, function($item) use (&$max) {
        if ($item > $max) {
            $max = $item;
        }
    });

    return $max;
}

echo array_max_recursive(["1", "2", ["3", "4"]]); // 4

Answer 2

What you want is a recursive function.

The function looks up the biggest element in a an array. If an item in the array is an array, it will find the biggest item in that array and use that to compare.

To find the biggest value in that array it will use the same function.

function findMax($arr){
    $max = 0;
    foreach($arr as $item){
        if(is_array($item)){
            $val = findMax($item);
        }else{
            $val = $item;
        }
        $max  = $val>$max?$val:$max;
    }
    return $max;
 }

Use example:

$arr = Array(1,2,Array(3,10,Array(6,7)));
$arr2 = Array(1,2,Array(3,5,Array(6,7)));
echo findMax($arr)."\n".findMax($arr2);

Result:
10
7